Covering material and method of making the same



Patented Apr. 23, 1935 UNITED STATES COVERING MATERIAL AND METHOD OF MAKING THE SAME Earl B. Grosh, Berkeley, Val Fish, Oakland, and Samuel A. Cohen, Berkeley, Calif., assignors to The Parafline Companies, Inc.,' San Francisco, Calif., a corporation of Delaware No Drawing. Application July 26, 1932,

' Serial No. 624,992

2 Claims.

Our invention relates to covering materials, and more particularly to'fioor coverings, such as linoleum, and to the method of making the same.

Floor coverings, such as linoleum, have a foun dation sheet which is formed by depositing on a fabric sheet, usually burlap, a plastic composition commonly comprising such materials as wood flour, cork dust and linoleum cement. The freshly formed foundation sheet is then subjected to a curing process in which the product is heat treated at a temperature of about 170 F. for a period of about fourteen days in suitable ovens or stoves. After the foundation sheet has been thus cured, it is the usual practice to ap ply a finishing coating.

The application of this finishing coating involves an additional step in manufacturing calling for additional handling of the cured materialt and thus brings about added manufacturing cos s. applied subsequently to the curing operation is not invariably bonded to the foundation sheet with the maximum degree of effectiveness, but for want of a better process the practice of applying the finishing coat after the stoving operation is accepted.

In view of the above and other considerations, it is among the objects of our invention to provide a method of making coated covering materials of the character described which eliminates the additional handling andequipment as well as the added time involved in the present method of applying the finishing coating, and which permits the covering material to be rolled up for storage or shipment directly upon completion of the curing of the foundation sheet.

Various materials have been used in the finishing coatings of floor coverings, depending upon the nature of the covering and the use to which it is to be subjected. .It is notable however that these coating materials have been lacking in one or more of the properties desired in a finishing coating. Among the properties which are deemed necessary in a finishing or surface coating for 45 high grade linoleums and the like floor coverings are:

l. The coating should be so tough and so thoroughly bonded to the linoleum that it is substantially abrasion proof.

2. It should be highly resistant to injury by water, soap, alcohol, acid, alkali, and all other substances to which it may ordinarily be exposed.

3; It should be free from after effects such as, yellowing, peeling, cracking, blistering, and other effects such as may'appear after the linoleum is laid.

4'. The coating should be of a nature such that the various types of finisheslmay be applied over it after the linoleum has been subjected to a pcriod of wear.

Furthermore, the finishing coating, when other kind after the linoleum has been placed in service, as the wax must be entirely removed before other finishes such as shellac, lacquer, or oil finishes may be applied. Furthermore waxes are slippery and hence objectionable in service. Shellac, while permitting the application of other coatings, is objectionable because it is whitened by water, and is cut by alcohol; and offers poor resistance to water, alkali, strong soap, and other substances to which it is likely to be exposed. Oilsand oil finishes of various kinds offer poor resistance to alkali, and have a pronounced tendency to strike in, that is, to be partially absorbed by the linoleum whereby an uneven finish is produced. Lacquer is objectionable because of the relatively poor bond formed with the linoleum, whereby the lacquer is easily marred or removed by abrasion. The infiammable nature of lacquer is also objectionable.

In View of the foregoing'and like considerations, other objects of our invention include the provision of an improved coating material which produces a coating having substantially all the properties deemed necessary in a high grade covering material, but which is characterized by the absence of the shortcomings noted in connection with the usual coating materials.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of our invention. It is to beunderstood that we do not limit ourselves to this disclosure of species of our invention, as we may adopt variant embodiments thereof within the scope of theclaims.

In terms of broad inclusion, the preferred method of making covering materials embodying our invention relates to materials having a foundation sheet which is cured by heat treatment, such as linoleum, and comprises preparing the foundation sheet and applying a finishing coating prior to the heat treatment of the sheet, so

that the product is ready for packing directly upon completion of the curing process. 'Our invention also contemplates the selection and treatment of appropriate bases and solvents which are emulsified with water to produce a coating material suitable for application to the raw or uncured foundation sheet of the covering material.

The base of the emulsified coating material preferably comprises a substance of the class of synthetic gums and resins, since a base of this character not only possesses properties which are desirable in the coating, but also further improves in desired qualities under heat treatment or baking, such as that to which the coating would be subjected in our preferred process. Our invention also embraces a method controlling the penetration of the coating into the foundation sheet of the covering material.

In greater detail, the preferred method of mak ing covering material embodying our invention pertains to the fabrication of materials having a foundation sheet which is cured by heat treatment, such as linoleum. The linoleum type of floor coverings have a foundation sheet which is formed by depositing on a fabric sheet, usually burlap, a plastic composition commonly comprising such materials as wood flour, cork dust and linoleum cement. In order to transform this material into a tough and durable sheet the same is subjected to a curing process in which the product is heat treated at a temperature of about 170 F. for a period of about fourteen days in suitable ovens or stoves.

As has already been pointed out, the practice heretofore has been to apply the finishing coating after the foundation sheet is cured. To avoid the added handling and time required by this practice, our method comprises applying the finishing coating prior to the heat treatment of the sheet, so that the finishing coating dries during the curing of the foundation sheet. By this method the covering material may be rolled up for storage or shipment directly upon completion of the curing process.

In order to provide a coating material which is suitable for application to a raw-or uncured foundation sheet, and to provide a coating which not only withstands the baking temperature of the curing process but improves in desirable qualities thereunder, our invention contemplates the selection of appropriate bases and solvents which are emulsified with water to produce a coating emulsion. In the selection of the base of our emulsion we have kept in mind the shortcomings of the coatings heretofore employed and have developed a coating which possesses substantially all the properties desired in the finishing coating of a covering material.

The base of our coating emulsion preferably comprises a substance of the class of gums and resins. For this purpose we have found that the synthetic gums and resins arepreferable, be-

cause of the wider range of properties which it is possible to obtain by varying the quantities of components, the temperature, the duration of treatment, and other variable factors during th synthesis of the gum or resin. Another impor-v tant property of the synthetic gums and resins resides in the fact that during the baking of the coating these substances in most instances under80 a conversion whereby they are rendered insoluble in the solvent from which they have just been deposited by the evaporation of the solvent. This characteristic lends itself to further increasing the resistance offered by the film to attack by agencies to which it may be exposed.

A wide variety of these synthetic gums and resins is available for use alone or in mixtures of two or more to obtain desired properties. We prefer to use a synthetic gum as a base, p eferably a glycerol phthalate having an acid number from 30 to 80 and a saponification number of from 200 to 600; the gum being soluble in hydrocarbons of benzene (CcHe) series, in ketones, esters, or ether alcohols, but soluble with difficulty in petroleum hydrocarbons or in ethanol. This gum belongs to the type of polybasic acid poly esters. Other phthalates of this group are ethylene glycol phthalate and pentaerythritol phthalate. Resinates of the vpolyhydric alcohols may be used, but these sometimes lack the flexibility and toughness desired after heat treatment. It is preferred that such esters be distinctly acid, but esters or resins of low acidity or which are neutral may be used if a suitable amount of organic acid is added before emulsification.

Phenol-aldehyde condensation resins, such as the phenol-formaldehyde product, may also be used, organic acid being added before emulsification, if necessary. This class'also includes the resins with the cresols and the xylenols as bases, or with furfural, or the ortho and para hydroxy diphenyls; or with acetaldehyde in place of formaldehyde. It is preferred to use resins of this class which are insoluble in petroleum hydrocarbons as well as in ethanol, but which are soluble in the hydrocarbons of the benzene series and in ketones and esters.

Where the requirements are not too exacting, other resins of this general class which are easily soluble in petroleum hydrocarbon or in ethanol,

may be used.

Numerous other gums and resins, both natural and synthetic, are susceptible for use in accordance with the present invention. For example where a slight brittleness is not objectionable, polymers of the cumarone-indene series may be used. These resins are non-saponifiable unless modified by saponifiable materials such as resins, fatty acid, fatty acid esters, anhydrides, or similar substances. The tendency toward brittleness may be largely corrected by use therewith of soft resins, or by adding suitable amounts of softening agents such as China wood oil, castor oil, or similar softeners. The vinyl polymers and the chlordiphenyls may be utilized in much the same manner. Natural gums, such as Congo, Manila, Kauri gums, may also be used, but in many cases these gums must be fused with other natural or synthetic resins to render the base soluble in a desired solvent.

The preferred solvent (where inflammability is not objectionable) is toluene. The higher members of the same series may also be used, xylene being particularly favored on account of its evaporating qualities. Mixtures of various members of the benzene-(Carla) series may beused, or mixtures of them with ketonic solvents or with esters, for instance pentacetate or butylacetate. It is often desired to use a solvent which is relatively or quite non-inflammable. In this case, ethylene dichloride is preferred. Other-chlorinated hydrocarbons such as trichlorethylene, tetrachlor ethane, and carbon tetrachloride may be used. Chloroform may also be used. In the case of some of the phenol-aldehyde condensation resins, petroleum hydrocarbons may be used as the solvent, one having a boiling point approximately the same as toluene being preferred.

For the emulsifier we prefer to use triethanolamine, though a large group of amines may be used. For example, ammonia, ethylamine and also amyl and butyl amines may be used. The main requirement is that the emulsifier shall be reactive with the acid content of the base. Mixtures of the amines may of course be used. The use of an excess of ammonia is objectionable as an excess tends to make a finish which is affected by water, whereas triethanolamine produces a finish which is highly resistant to the action of water. Soap may also be used to efiect emulsification or to aid in emulsifying the gum-solvent mixture. Sodium resinate may be used in this manner. Sodium or potassium oleate, stearate' or palmitate in water solution 'either alone or in combination, or mixed with triethanolamine may also be used.

The following examples typify our preferred practice in preparing the coating emulsion:

Example 1 Percent Glycerol phthalate"; 12.5 Toluene 48.1 Triethanolamine 0.9 Water 38.5

Example 2 26 kilograms of glycerol phthalate are dissolved with. 100. kilograms of ethylene dichloride and mixed with a solution of 2 kilograms of triethanolamine in 80 kilograms of water. 50 kilograms of ethylene dichloride are then added to the mixture to extend the emulsion, the percentage composition of which is:

Percent Glycerolphthalate 10.0 Ethylene dichloride 58.2 Triethanolamine 0.8 Water 31.0

The emulsion is preferably applied to the raw foundation sheet in. the course of manufacture of the covering material, immediately before the uncured foundation sheet is delivered to the oven in which it is stoved or subjected to heat treatment for curing. The emulsion may be applied by any suitable means, as by applicator rolls arranged to deliver the emulsion from a fountain to the surface of the foundation sheet, or the emulsion may be sprayed upon the surface of the sheet. If desired, the emulsion may be delivered to the surface of the sheet by suitable means and spread with doctors.

In the emulsion, the toluene or ethylene dichloride solution seemingly forms the outside phase, and the water solution the inside phase. When the emulsion is applied to the surface of the foundation sheet, there appears to be a phase reversal. As a result, the water wets the sheet surface, and the minute globules of dispersed base-solvent are not immediately brought into contact with the sheet surface, and hence they undergo a certain amount of evaporation along with the water. By the time the base-solvent comes into contact with the sheet surface it has. become too viscous to penetrate or strike in to any material degree. This results in producing a uniform finish giving throughout a texture genrally classed as eggshell.

In the absence of water to wet the surface of the foundation sheet a base-solvent alone tends toward excessive penetration over some areas thereby producing a flat lusterless appearance over such areas, while other areas having slightly thicker coatings will dry glossy. It therefore appears that thewater component of the emulsion and its phase relation therein serves as a means of controlfor the penetration of the coating material and consequently the character of the drying film and the nature of the resultant finish. We have found that the penetration and consequently the final finish may be materially varied by increasing or decreasing the proportion of water, but for ordinary purposes, the proportions hereinabove given are preferred. The finish may also be somewhat varied by increasing or decreasing the amount of solvent present.

After the emulsion has been applied to the surface of the foundation sheet, the coated sheet is delivered to the ovens and subjected to the usual heat treatment, for linoleum this is at a temperature of about 170 F. for a period of about fourteen days. The heat treatment causes the finish coating to be baked onto the surface of the linoleum. This results in a film which is extremely tough and highly resistant to attack by water, alkali, acid, or by any of the agencies to which the surface is ordinarily exposed. At the same time, the film is sufficiently flexible to permit the linoleum to be rolled in conveniently small rolls. Furthermore, the film will permit the application of any ordinary finish which may be applied after the linoleum has been laid and exposed to wear.

While we prefer to apply the finishing coating in the course of manufacture prior to the delivery of the foundation sheet to the ovens. a satisfactory product can be obtained if the coat is ,Percent Glycerol phthalate 12.5 Toluene 48.1 Water 38.5 Triethanolamine 0.9

2. The method of making linoleum, which comprises applying a finish coating on the uncured plastic body of the linoleum, and then subjecting the whole to a temperature of about 170 F. for about fourteen days, said finish coating comprising an emulsion of the approximate proportion of:

Percent Glycerol phthalate 10.0 Ethylene dichloride. 58.2 Water 31.0

Triethanolamine 0.8

EARL B. GROSH. VAL FISH. SAMUEL A. COHEN. 

